Emerging powers have tried to build functional regional power bases in their respective spheres of influence to gain support for their leadership projects and representative capacities on the global stage. This has caused diverse contestational responses by secondary powers in different regional orders. In this context, we analyse the shift of C olombia's contestation approach towards the B razilian leadership claim in S outh A merica. With the arrival of P resident S antos, C olombia turned from collateral hard balancing against B razil to institutional contestation through the P acific A lliance. Besides furnishing evidence of the broader C olombian soft‐balancing strategy in other policy areas, the article explores and balances the domestic, structural and behavioural drivers of the strategic turn to institutional contestation through the P acific A lliance without neglecting the economic and political motives of C olombia's engagement in the pro‐market alliance.